A shackle is a metal link, typically U-shaped or D-shaped, closed by a bolt or pin (threaded preferably with regard to the invention) referred to as a clevis or shackle pin. A clevis is a type of shackle but is used equivalent to the shackle herein. A clevis or shackle pin is used to fully enclose the shackle or clevis providing an attachment means between combinations of load members.
Bow shackles and anchor shackles are terms that are often used interchangeably, as both names refer to a shackle with a larger, rounded “O” shape look. However, a bow shackle typically has a larger, more defined bow area than an anchor shackle. The rounded design of anchor shackles and bow shackles allow them to take loads from many directions without developing significant side load. The larger loop shape of an anchor shackle or bow shackle does reduce its overall strength, but it is also able to handle a larger strap
Chain shackles are also known as D-shackles. Both refer to the “D” shape design. A d-shackle is narrower than a bow or anchor shackle and generally have a threaded pin or pin close. The smaller loop is designed to take high loads primarily in line. Side and racking loads may twist or bend a D or chain shackle.
Governmental safety organizations state not to use screw pin shackles or fit pins in contact with moving parts if the pin can roll and unscrew. OSHA 1918.62(i)(2) states “Screw pin shackles provided by the employer and used aloft, except in cargo hook assemblies, shall have their pins positively secured.” If the load shifts, the sling will unscrew the shackle pin. Also governmental safety organizations such as OSH of Canada state not to use round pin shackles restrained only by a cotter pin for overhead lifting.
A shackle is a device used for fastening. Many shackles are U, D, or C shaped, but the shackles may come in various other shapes. Screw pin type shackles are the most commonly used shackle. Screw pin type shackles generally have two opposing sides that are joined together by an arch shaped piece which forms the U, D, or C shape. One side of the shackle has a threaded hole (hereinafter the threaded side of the screw pin type shackle) and one side is not threaded (hereinafter the non-threaded side of the screw pin type shackle). The shackle pin has one end that is threaded (hereinafter the threaded end of the shackle pin) and one end that has a head (hereinafter the shackle pin head). The shackle pin head may include an aperture. The threaded end of the shackle pin passes through the non-threaded side of the shackle and then threads into the opposing threaded side of the shackle to secure the shackle pin in place.
Screw pin type shackles are commonly used in industrial applications for lifting and rigging. Screw pin type shackles are also commonly found in sailing. A major concern when using screw pin type shackles is the possible disengagement of the shackle pin from the threaded side of the screw pin type shackle while lifting. If the shackle pin were to disengage, serious damage, injury, or even death may result. When using a screw pin type shackle, a common practice to prevent the shackle pin from disengaging is to mouse the shackle. Mousing is a technique that uses wire, rope, or other materials such as zip ties. Such materials are inserted through the aperture in the shackle pin head while the shackle pin is engaged and passed around the non-threaded side of the shackle and back to itself thus preventing the shackle pin from being able to roll. Problems with this mousing technique include but are not limited to, the use of non-reusable materials, the necessity of other tools for installation, the requirement of knowledge of proper technique to effectively secure the shackle pin, the potential damage to personnel and/or rigging that may result, the difficulty of performing without good visibility, and the time consuming nature of the technique.
What has been needed for shackles is a method, system, and apparatus with attributes included, but not limited to; ease of use, applicable to screw pin and anchor type shackles (most common shackle type), flexible use (fits multiple size shackles and multiple brands of shackles), stores in shackle pin when not in use, saves time vs traditional moussing techniques, difficult to be installed incorrectly, no tools required, no loose parts or pieces, prevents injury from pokes of sharp wire when moussing, prevents sling damage and chaffing from moussing wire ends, no single use consumables like rope, wire or zip ties (reusable), turns anchor and screw pin shackles into safety shackles, using the device doesn't change rigging practices or techniques, works with old or new shackles, works with bow shackle, anchor shackle, chain shackle, twist shackle, head board shackle, C-D-U shaped shackles, can be used in zero visibility, saves attachment and detachment time over a traditional method, system, or apparatus.